#!/usr/bin/perl
# - Example threading code reading from multple files being slow 
use strict;
use warnings;
use threads;
use Thread::Queue;

my @files = qw( 
	SyslogR_20110615_134243.txt SyslogR_20110615_162146.txt 
	SyslogR_20110620_090237.txt SyslogR_20110620_090308.txt 
	SyslogR_20110620_092240.txt SyslogR_20110620_092328.txt
);


non_thread_process( \@files);
my $PARALLEL = 1;
thread_process( \@files);
$PARALLEL = 4;
thread_process( \@files);

sub non_thread_process {
	my $args=shift;
	for my $file (@$args) {
		process($file, "Non Thread");	
	}
}

sub thread_process {
	my $args = shift;
	my @threads;
	my $queue = Thread::Queue->new();
	for my $p ( 1 .. $PARALLEL ) { 
		push @threads, threads->create( sub {
			while( my $file = $queue->dequeue) { 
				process($file, "Thread $p of $PARALLEL");
		}})
	}
	$queue->enqueue( @$args, (undef) x $PARALLEL );
	$_->join for @threads;
	return 1;
}

sub process {
	my ($file, $msg) = @_;
	my $start =time;
	open my $IN, $file or die "Cannot read file $file : $!";
	while(<$IN>) {
		my @x= split/ /; # Do something
	}
	close $IN;	
	my $end =time;
	printf "$msg: Process of $file complete in %ds\n", $end-$start;
}
__END__
$ perl -v

This is perl, v5.10.1 (*) built for i686-cygwin-thread-multi-64int
(with 13 registered patches, see perl -V for more detail)

Copyright 1987-2009, Larry Wall

Perl may be copied only under the terms of either the Artistic License or the
GNU General Public License, which may be found in the Perl 5 source kit.

Complete documentation for Perl, including FAQ lists, should be found on
this system using "man perl" or "perldoc perl".  If you have access to the
Internet, point your browser at http://www.perl.org/, the Perl Home Page.

$ perl ./example.pl


Non Thread: Process of SyslogR_20110615_134243.txt complete in 0s
Non Thread: Process of SyslogR_20110615_162146.txt complete in 1s
Non Thread: Process of SyslogR_20110620_090237.txt complete in 0s
Non Thread: Process of SyslogR_20110620_090308.txt complete in 1s
Non Thread: Process of SyslogR_20110620_092240.txt complete in 0s
Non Thread: Process of SyslogR_20110620_092328.txt complete in 1s
Thread 1 of 1: Process of SyslogR_20110615_134243.txt complete in 0s
Thread 1 of 1: Process of SyslogR_20110615_162146.txt complete in 1s
Thread 1 of 1: Process of SyslogR_20110620_090237.txt complete in 0s
Thread 1 of 1: Process of SyslogR_20110620_090308.txt complete in 0s
Thread 1 of 1: Process of SyslogR_20110620_092240.txt complete in 1s
Thread 1 of 1: Process of SyslogR_20110620_092328.txt complete in 0s
Thread 4 of 4: Process of SyslogR_20110620_090308.txt complete in 11s
Thread 1 of 4: Process of SyslogR_20110615_134243.txt complete in 16s
Thread 3 of 4: Process of SyslogR_20110620_090237.txt complete in 24s
Thread 2 of 4: Process of SyslogR_20110615_162146.txt complete in 29s
Thread 1 of 4: Process of SyslogR_20110620_092328.txt complete in 14s
Thread 4 of 4: Process of SyslogR_20110620_092240.txt complete in 19s